I'm working on an iPhone app, and I'm wondering if I could run some code segment for only once (in other words: an initialization code, that I want it to be executed only at the very first run).
Here's my code, that I execute it at didFinishLaunchingwithOptions method:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
// Add the tab bar controller's view to the window and display.
[self.window addSubview:tabBarController.view];
[self.tabBarController setSelectedIndex:2];
[self.window makeKeyAndVisible];
[self createPlist1];
[self createPlist2];
[self createPlist3];
return YES;
}
I want the last three messages to be executed only at the very first run. I thought I could use the UserDefaults and set a key after these messages executes (at the first run) and check for the value of that key at each run, but I'm feeling that there's a better idea -which I don't know.
Thanks in advance.
Using a setting (via NSUserDefaults) is how it's normally done. For added benefit, give the setting the meaning of "last run version"; this way, you'll get a chance to run code not only once per app lifetime, but also once per version upgrade.
That said, your run-once code has persistent side effects, right? Those plists go somewhere probably. So you can check if they exist before creating them. Use the result of the run-once code as a trigger for running it again.
EDIT:
NSUserDefaults *Def = [NSUserDefaults standardUserDefaults];
NSString *Ver = [Def stringForKey:#"Version"];
NSString *CurVer = [[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleVersionKey];
if(Ver == nil || [Ver compare:CurVer] != 0)
{
if(Ver == nil)
{
//Run once per lifetime code
}
//Run once-per-upgrade code, if any
[Def setObject:CurVer forKey:#"Version"];
}
A much simpler possible solution ->
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if ([defaults objectForKey:#"FirstTimeBool"]==nil)
{
[defaults setObject:#"YES" forKey:#"FirstTimeBool"];
... //Code to be executed only once until user deletes the app!
...
this is what I used:
static dispatch_once_t once;
dispatch_once(&once, ^ {
// run once code goes here
});
I think you're on the right track with the User Defaults, something like:
-(BOOL)isInitialRun
{
NSNumber *bRun = [[NSUserDefaults standardUserDefaults] valueForKey:#"initialRun"];
if (!bRun) { return YES; }
return [bRun boolValue];
}
-(void)setIsInitialRun:(BOOL)value
{
[[NSUserDefaults standardUserDefaults] setBool:value forKey:#"initialRun"];
}
Then in your app delegate:
if ([self isInitialRun])
{
[self createPlist1];
[self createPlist2];
[self createPlist3];
[self setIsInitialRun:NO];
}
To my knowledge, the way you propose is the only option. Save a key to NSUserDefaults after you ran it for the first time and check for the existence of said key.
You could however, also check in each of your functions (the createPlist1 - 3 functions) run a check if the PList is already there. Would be a bit cleaner.
One thing I would add to #Seva Alekseyev answer:
After you make any changes (i.e. [Def setObject:CurVer forKey:#"Version"];) you should call [Def synchronize]
I had a problem where changes made to NSUserDefaults using setObject were not getting saved, until I used synchronize.
Related
I have a default UITabBarApplication with default views and tabs... etc. I have eight tabs that have the customizable option, so users can reorder tabs.
How do I get the order of the tabs, save that into NSUserDefaults and retrieve it when the app loads back up. I'd like to see some code examples.
Here is where I'm at so far:
- (void)applicationWillTerminate:(UIApplication *)application {
/*
Called when the application is about to terminate.
See also applicationDidEnterBackground:.
*/
NSMutableArray *vcArray = [NSMutableArray arrayWithCapacity:8];
NSArray *savedViews = tabBarController.viewControllers;
for (UIViewController *theVC in savedViews){
[vcArray addObject:theVC.title];
}
[[NSUserDefaults standardUserDefaults] setObject:vcArray forKey:#"tabLayout"];
}
- (void)tabBar:(UITabBar *)tabBar didEndCustomizingItems:(NSArray *)items changed:(BOOL)changed {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSArray *tabLayout = [defaults arrayForKey:#"tabLayout"];
NSMutableArray *orderedLayout = [NSMutableArray arrayWithCapacity:8];
NSArray *defaultOrder = tabBarController.viewControllers;
for (int i =0; i < 8; i++){
for (UIViewController *theVC in defaultOrder) {
if ([theVC.title isEqualToString:[tabLayout objectAtIndex:i]]) {
[orderedLayout addObject:theVC];
}
}
}
tabBarController.viewControllers = orderedLayout;
}
This code doesn't seem to work in the simulator. I reorder the tabs and hit done then stop the app, but when I hit build and run again the app reverts to default. Why isn't the code above working?
Thanks.
One comment:
NSUserDefaults don't always work with the simulator. If you're doing a new build each time, then of course everything gets reset.
Two suggestions:
put an NSLog in the latter method to make sure that it's being called
build the app to a device, move the tabs around, close the app (completely -- not just in background), open the app again, behold what happens.
I'm trying to add a Lifetime achievement to my iOS app. That is, how many times the user performed the single action since he played the game for the first time. In other words, how many kills he got since... ever. I'm using the code based on the one provided by Apple:
.h file:
int64_t lifetimeScore;
IBOutlet UILabel *lifetimeScoreLabel;
.m file:
- (IBAction) increaseScore {
self.lifetimeScore = self.lifetimeScore + 1;
lifetimeScoreLabel.text = [NSString stringWithFormat: #"%ld", self.lifetimeScore];
// Saving the Score:
NSUserDefaults * defaults = [NSUserDefaults standardUserDefaults];
[defaults setInteger:lifetimeScore forKey: #"Score"];
[defaults synchronize];
[self checkAchievements]; }
- (void)viewDidLoad {
[super viewDidLoad];
// Loading the Lifetime Score:
self.lifetimeScore = [[NSUserDefaults standardUserDefaults] integerForKey: #"Score"];
lifetimeScoreLabel.text = [NSString stringWithFormat: #"%ld", self.lifetimeScore];
(...)
}
I works great, no warnings, but each time I close the app, deletes it from the Multitask bar and open the app again, the lifetimeScore goes back to zero. I'm trying to save the int_64 using NSUserDefaults but so far I can't make it work... any ideas?
EDIT: The code was fixed and now it's working 100% in case anyone wants to use it. The complete source code can found here: http://mobile.tutsplus.com/tutorials/iphone/ios-sdk-game-center-achievements-and-leaderboards-part-2/
#"Store" should be #"Score", just so I can get the points... :)
I've been told that I need to use the registerDefaults: to load the NSUserDefaults if the user has never changed the app settings.
In my AppDelegate I am using the following code:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
// Load default defaults
[[NSUserDefaults standardUserDefaults] registerDefaults:[NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"Defaults" ofType:#"plist"]]];
[[NSUserDefaults standardUserDefaults] synchronize];
// Add the view controller's view to the window and display.
[window addSubview:viewController.view];
[window makeKeyAndVisible];
return YES;
}
I copied the Root.plist of my settings bundle to the ressources folder of my project and renamed it Defaults.plist
Now in the viewDidLoad method of my view controller i'm using the following code to load the settings:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if ((([[defaults objectForKey:kToggleSwitch] isEqualToString:#"Enabled"]) ? YES : NO)) {
//Do Stuff
//BTW i'm using strings for the True/False the values of the ON/OFF positions of the UISwitch
}
Even with doing all this, my default settings stored in the Root.plist of my settings bundle don't get loaded. The only way they load is if the user actually goes into the iPhone settings and simply views my app's settings page.
Clearly i'm doing something wrong here can someone help me out. Btw i'm running it using iOS 4.1
when I made my app, i never knew of any defaults to be registered, so I made a poor man's defaults:
I have a bool variable: haveConfig, which is checked when the settings are loaded:
haveConfig = [prefs boolForKey:#"haveConfig"];
if (!haveConfig)
{
return;
}
/* Load settings here */
....
First time the "haveConfig" will be false, so I don't load them. When the user first changes one of the settings, they are stored together with the "haveConfig" variable:
haveConfig = true;
[prefs setBool:haveConfig forKey:#"haveConfig"];
...
I know it's not perfect, but it works :-)
Will this be done on every launch of the app? Since it is in the applicationDidFinishLaunching method. Is there a way to do this once and for all?
Thanks!
Hi you can take advantage of preferences..
here is the code to determine application is running for first time or not:(check this in applicationDidFinishLaunching method.)
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
if([defaults objectForKey:#"Remote_Notification_Registered"] == nil)
{
// This is first run ...
// Do your only one time initialization
[defaults setValue:#"1" forKey:#"Remote_Notification_Registered"];
}
else
{
// Not first run
}
Hope this will help.
I have saved data which was saved using NSUserDefaults. I was under the impression that if there was nothing saved to the key already (first time app is run) it would default to 0. This however doesn't seem to be the case.
Here is what I have:
To save:
- (void)viewWillDisappear:(BOOL)animated
{
[[NSUserDefaults standardUserDefaults] setInteger:setbatteryHealthCalculated forKey:#"healthValue"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
To load:
- (void) viewWillAppear:(BOOL)animated
{
NSInteger setbatteryHealthCalculated = [[NSUserDefaults standardUserDefaults] integerForKey:#"healthValue"];
}
To check for save value:
- (IBAction)check{
NSInteger setbatteryHealthCalculated = [[NSUserDefaults standardUserDefaults] integerForKey:#"healthValue"];
if (setbatteryHealthCalculated = 0) {
[self performSelector:#selector(displayAlert) withObject:nil];
}
}
if (setbatteryHealthCalculated = 0) {
Ehm. Should be
if (setbatteryHealthCalculated == 0)
The comparison operator is == instead of = in C-like languages.
The original code will set setbatteryHealthCalculated to 0 no matter what. Since 0 is false, the if branch will never be executed and no alerts would be shown.
Also, the original code has unbalanced braces.
BTW, is setbatteryHealthCalculated an ivar? If yes, remove the NSInteger before it. Otherwise you're declaring a local variable which shadows the ivar.
Call registerDefaults: during your app's launch to set default values for your defaults (awkward to say, but that's how it work). You'll need to call it before any of the code that accesses your defaults. But NSUserDefaults does return 0 or nil for keys that don't exist.